1. Field of the Invention
The present invention relates to sintered compacts, cutting tools formed using sintered compacts, and methods for manufacturing sintered compacts, and more particularly to sintered compacts containing cubic boron nitride, cutting tools formed using such sintered compacts, and methods for manufacturing such sintered compacts.
2. Description of the Related Art
Sialon (also written as “SiAlON”) is silicon nitride having aluminum and oxygen dissolved therein and takes two types of crystal forms, namely, α-type and β-type, which belong to the hexagonal system (hereinafter referred to as “α-sialon” and “β-sialon”). Sintered compacts containing sialon have been studied as a cutting tool material for their low reactivity with workpieces.
For example, Japanese Patent No. 2849055 discloses a sialon-based sintered compact based on α-sialon and/or β-sialon, with the balance including a composite oxide of a rare earth element, a group 4 element, and at least one of group 2, 6, 7, and 8 elements.
Japanese Unexamined Patent Application Publication No. 2005-212048 discloses a ceramic containing Si3N4 or sialon particles bound together with a metal and/or an alloy in an amorphous phase.
The above sialon ceramics have low reactivity with workpieces, although they have a lower hardness than cubic boron nitride and exhibit insufficient wear resistance when used as a cutting tool material.
In view of hardness and reactivity with workpieces, therefore, there is a need for a sintered compact that can be used as a cutting tool material to form a cutting tool having both superior wear resistance and superior fracture resistance.